1. Field of the Invention
The present invention relates to packer inflation systems, and more particularly to valving apparatus which control the inflation of packers.
2. Description of the Background
Control over the inflation of well packers is important to obtain integrity between the packer and the well bore for sealing the annular cavity about a well casing or other tubular element. It is commonly known that the packers may be inflated by various mechanisms, some of which are, for example, U.S. Pat. Nos. 3,503,445, 3,351,349, and 3,373,820.
George Conover in U.S. Pat. No. 3,437,142, issued in 1969, disclosed an inflatable packer for external use on tubular members such as casings, liners, and the like. A valving arrangement is disclosed therein for containing fluid within the interior of the inflatable member after it has been inflated to prevent its return to the tubular member.
Valving arrangements have been known in the prior art to prevent further communication between the interior of the tubular member and the interior of the inflatable element after the inflatable element has been inflated and set in a well bore. Baker et al. in U.S. Pat. No. 4,260,164 teaches such an arrangement wherein its second valve moves from an open position to a closed position and is held in the closed position by a metal retaining ring which engages a counterbore to permanently isolate the interior of the tubular member from the interior of the inflatable element. Other examples of locking means to lock a valve in closed position to prevent further communication between the interior the tubular member and the interior of the inflatable element when the valve closes may be seen in U.S. Pat. Nos. 3,818,922 and 3,776,308. For further examples of valving arrangements to prevent further communication between the interior of the tubular member and the interior of the inflatable element after the inflatable element has been inflated and set in a well bore see, for example, U.S. Pat. Nos. 3,427,651, 3,542,127 and 3,581,816.
A valving arrangement is disclosed in U.S. Pat. No. 4,420,159 to permit the inflation of an inflatable packer element while at the same time equalizing pressure around the rubber seals of the valve or valves to prevent distortion of the seals from undue high differential pressure, and the resulting friction.
Inflatable packers have also been used in other operations, such as sealing the annular space between a jacket and a piling. For an example of this, see U.S. Pat. No. 4,063,427.